Topological Quantum Phase Transition in 5$d$ Transition Metal Oxide Na$_2$IrO$_3$

TL;DR

This paper predicts a quantum phase transition in Na$_2$IrO$_3$ from a normal to a topological insulator driven by changes in hopping and crystal field effects, highlighting its potential as a topological material.

Contribution

It introduces a first-principles-based analysis of topological phase transitions in Na$_2$IrO$_3$, identifying key parameters influencing its topological state.

Findings

Phase boundary determined via parity analysis.

Interlayer distance influences topological phase.

Na$_2$IrO$_3$ can host both nontrivial topology and strong correlations.

Abstract

We predict a quantum phase transition from normal to topological insulators in the 5$d$ transition metal oxide Na$_2$IrO$_3$, where the transition can be driven by the change of the long-range hopping and trigonal crystal field terms. From the first-principles-derived tight-binding Hamiltonian we determine the phase boundary through the parity analysis. In addition, our first-principles calculations for Na$_2$IrO$_3$ model structures show that the interlayer distance can be an important parameter for the existence of a three-dimensional strong topological insulator phase. Na$_2$IrO$_3$ is suggested to be a candidate material which can have both a nontrivial topology of bands and strong electron correlations.